The field of this disclosure relates generally to adhesive compositions and, more particularly, to adhesive compositions that contain thermally conductive carbon-based materials that are also electrically insulated. Other aspects of the disclosure relate to methods for using such adhesive compositions and methods for their preparation.
Manufacture of electronic devices conventionally requires use of adhesive compositions. The adhesive compositions are used to attach electronic components (e.g., chips and resistors) to a target surface within the device such as a mounting surface or heat sink surface. It is desirable, in some instances, to use a thermally conductive adhesive composition (i.e., a composition that transmits heat well) so that the heat generated by the electronic component may easily pass through the adhesive to a heat sink (e.g., an aluminum or copper alloy in the device) and overheating of the device may be prevented.
Thermally conductive materials are typically also electrically conductive. As a result, when a portion of the adhesive (and particularly the filler material of the adhesive such as various metals) in conventional electronic devices dislodges due to age or repeated transport of the device (e.g., as in handheld devices or devices used in transportation), the electrically conductive components of the adhesive may contact an active region of the device and may cause the device to short-circuit. Such events may potentially cause failure of the device. Furthermore, if the composition of the adhesive is adjusted to increase its thermal conductivity (e.g., by incorporation of greater amounts of metal), the electrical conductivity of the adhesive may increase to a point at which the adhesive becomes electrically conductive causing a short-circuit of the device. Accordingly, the material is often packaged in ceramic or plastic packaging which increases the cost of the device.
A need exists for adhesive compositions that are not electrically conductive but which have a high thermal conductivity, allowing for transfer of heat from a heat generating component to a heat sink. A need also exists for processes for preparing such adhesive compositions and for using the compositions in electrical devices.